Spiral slot antenna



c. E. SMITH SPIRAL SLOT ANTENNA Nov. 5, 1957 Filed April 14. 1955 2Sheets-Sheet 1 Nov. 5, 1957 c. E. SMITH 2,812,514

SPIRAL SLOT ANTENNA Filed April 14, 1953 2 Sheets-Sheet 2 DEVEL OPME N7' IN V EN TOR.

BY CPA/PL. E. SM/TH United States Patent C) SPIRAL SLOT ANTENNA Carl'E.Smith, Cleveland Heights, Ohio Application April 14, 1953, SerialNo.348,606

29 Claims. (Cl. 343-767) The invention relates in general to antennasfor use with electromagnetic wave energy, and more: particularly toconduits or hollow cylinders having slots therein for the radiation ofthe radiant energy waves.

An object of the invention is to provide an antenna having a high gainin the horizontal plane, with low wind resistance and with greaterflexibility of control of the horizontal field intensity pattern for agiven number of feed lines than is possible with normal dipoles.

Another object of the invention is to provide an antenna having auniform gain in the horizontal plane and which is capable of beingvertically stacked to increase the gain in the horizontal plane.

Another object of the invention is to provide an antenna to radiatecircularly polarized electromagnetic waves with the horizontal fieldintensity pattern highly controllable as to nulls and/or circularity.

A further object of the invention is to provide a hollow cylindricalantenna having a spiral slot for effecting radiation of electromagneticwaves having both horizontal and vertical components.

A further object of the invention is to provide a hollow cylindricalantenna having edges defining slot means with both a vertical and ahorizontal component to effect circular polarization of the radiatedelectromagnetic wave with a high uniform gain in the horizontal plane.

A further object of the invention is to provide a hollow cylindricalantenna having a plurality of slots twisting in a first direction and aplurality of slots twisting in the opposite direction.

A further object of the invention is to provide a conduit means havingspiral slots therein wherein the slots are connected to transmissionlines which may be either open wire lines or coaxial cable.

Another object of the invention is to provide an electrically conductingconduit means having an axis with a first slot having a right handspiral relative to the axis and a second slot having a left spiralrelative to the axis and each connected to transmission lines ofdifferent phase inorder to achieve an antenna coupled to free space foreither ellipticall-y polarized or circularly polarized electromagneticwaves.

Other objects and a fuller understanding of the invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawing, in which:

Figure 1 is a perspective view of a hollow cylindrical antenna having aright and left hand spiral slot;

Figure 2 is a cross-sectional elevational view taken along the line 2-2of Figure 1;

Figure 3 is a cross-sectional view taken, along the line 3--3 of FigureI;

Figure 4 is a perspective view of a hollow cylindrical antenna havingone spiral slot;

Figure 5 is a crossrsectional view taken along the line 5 5 of Figure 4;

Fatented Nov. 5, 1957 ice Figure 6 is a front elevational view ofanother forni of spiral slot antenna;

Figure 7 is an end view of. Figure 6;

Figure 8 is a side elevational view of Figure 6; and

Figure 9 is a developed view of the spiral slot antenna of Figures 6 and8.

The invention deals with antennas that have a slot or slots in aconduit, which conduit has been shown in the drawings and is preferablyin the form of a hollow cylinder for the sake of symmetry. For furthermodifications of the invention reference may be had to the parentapplication filed October 16, 1947, entitled Slotted CylindricalAntennas, Serial No. 780,264, now Patent No. 2,665,381, issued January5, 1954, of which this application is a continuation-in-part, and ThreeSlot Cylindrical Antenna, filed October 16, 1947, Serial No. 780,265,now Patent No. 2,665,382, issued January 5, 1954. The preferredembodiment of the invention is shown in the Figures 1, 2, and 3 whereintwo oppositely rotating spiral slots are fashioned in a hollow cylinder108. The cylinder 108 is shown as being supported by a mast 109, and. isfastened to the mast 109 by supports 110. First and second edges 111 and112 define a first slot 115, which is a left hand spiral slot. Third andfourth edges 113 and 114 define a second slot 116, which is a right handspiral slot. The first and second spiral slots 115 and 116 are each madeone wave length long, and each is inclined 45 degrees to the axis of thecylinder 108. The diameter of the cylinder 108 has been chosen such thateach slot 115 and 116 makes one complete revolution about the peripheryof the cylinder 108. The supports that fasten the cylinder 108 to themast 109, are placed at a voltage minimum point of the antenna, whichvoltage minimum points are produced at points equidistant from thevarious slot edges. There. are four such points in the antenna as shownin the Figures 1, 2, and 3, and the supports 110 have been located atsuch voltage minimum points. First and second coaxial cables 117- and118 are used to feed the first and second slots and 116. These first andsecond coaxial cables 117 and 118 have been omitted from the perspectiveview of Figure 1 for the sake of clarity in this view. The first coaxialcable 117 extends through a hole 119 in the mast 109 at a point adjacentto one of the supports 110, and electrically contacts the inner surfaceof the cylinder 108 at this point. The first coaxial cable 117 thenextends upwardly to reach the mid-point 106 of the first spiral slot115-. The outer shell of the coaxial cable 117 ends at the second edge112, and the inner conductor of the coaxial cable 117 extends across theslot 115 to connect to the firstedge 111 A second coaxial cable 118extends through a hole 120 in the mast 109 adjacent to a support 110 andconnects to the inner surface of the cylinder 103. From this pointadjacent the support 110' the coaxial cable 118- extends upwardvertically to reach the mid-point 107 of the second slot 116. The outershell of the coaxial cable- 118 ends at the fourth ed'ge 1'14, and theinner conductor of the coaxial cable 118 extends across the second slot116 to connect to thethird edge 113 atthe mid-point 107.

ln the. antenna of Figures 1, 2, and 3, it will be noted that the lowerhalf of upper slot 116, and the-upper half of lower slot 115 togetherform a substantially continuous slot which is generally elliptical, andhas parallel sides. 111' and 112, and 113 and 114. Such substantiallycontinuous slot. extends completely around the antenna periphery, andis-fed by the coaxial cables 1-17 and 118. Thus because of thiscontinuous slot, the cylindrical antenna 108 may be considered as being.formed from an electrically conductive conduit defined by first andsecond sections, one above, and one below, the continuous slot.

The first and second slots 115 and 116 each have a horizontal componentand a vertical component, and hence the electromagnetic wave emanatingfrom the spiral slots have both vertical and horizontal components. Thehorizontal field intensity patterns of both the horizontal andvertically polarized electromagnetic waves of this antenna are verynearly circular.

The antenna shown in Figures 4 and 5 is a simplified version of theantenna shown in Figures 1, 2, and 3, inasmuch as the antenna comprisesa cylinder 122 having only one spiral slot. First and second edges 123and 124 define a slot 125 which has been shown as a left hand spiralslot. Slot 125 makes a 45 degree angle with the axis of the cylinder122. The length of the slot 125 has been made equivalent to one wavelength, and the diameter of the cylinder 122 has been chosen such thatthe slot 125 will complete one revolution about the periphery of thecylinder 122. A coaxial cable 126 is used to feed the slot 125, and isshown as being fastened to the inner surface of the cylinder 122 andaxially aligned therewith. The outer shell of the coaxial cable 126 endsat the midpoint 121 of the slot edge 124, and the inner conductor of thecoaxial cable 126 extends across the slot 125 to connect to the edge 123at the mid-point 121. A novel feature of the antenna shown in Figures 4and 5 is that the cylinder 122 needs no separate support, the cylinder122 may support itself. .The slot 125 in the cylinder 122 simulates aslot formed in a hollow flagpole-like structure.

Satisfactory radiation may be obtained from the antenna shown in Figures4 and 5, and substantially circular horizontal field intensity patternsof both the horizontal and vertically polarized waves may be attained.

The slots may be of any practical width and in practice are madesufliciently wide in order to develop the necessary potential differencethereacross Without arcing. The slot width is also sufiicient to preventicing or bridging across the slot by sleet formation which would shortthe slot..

The Figures 6 to 9 show another form of the invention wherein an antenna11 is carried on a mast 12. The antenna 11 is particularly adapted foruse with elliptically polarized or circularly polarized electromagneticwaves, either as a transmitting or a receiving antenna. The antenna 11may be placed at any convenient height above the ground. and for thispurpose the lower end of the mast 12 would be extended to the desiredlength. The Figure 9 shows a developed view of the diamond-shaped panelswhich form the antenna 11, and in this view the mast has been removedfor clarification. The antenna 11 is made from eight panels, 13 to 20,inclusive. Each of the panels 13 to 29 is supported from the mast 12 byinsulating spacers 21. These spacers 21 are located at each corner ofeach panel. Four feed holes 22 are cut in the mast 12 to expose first,second, third, and fourth feed lines 23, 24, 25, and 26. The panel has aside 27, and the panel 16 has a side 28 which are adjacent to form aslot 29. A feeder line 30 extends from the center of side 27 through oneof the feed holes 22 and is connected to the first feed line 23. Asecond feeder line 31 extends from the side 28 through the same feedhole 22 to the second feed line 24.

The first panel 13 has a side 34 adjacent a side 35 on the panel 14 toform a second slot 36. The center of the side 34 is connected by afeeder line, not shown, to the first feed line 23; and the center of thesecond side 35 is connected by a feeder line, not shown, to the secondfeed line 24. The panels 15 and 16 then become a dipole, and the panels13 and 14 become another dipole; and these pairs of dipoles areenergized in phase and in the same spiraling direction. Each of theslots 29 and 36 circumscribe approximately one-quarter of the peripheryof the conduit and are approximately a half wave length long althoughthey may be anywhere from four-tenths to seven-tenths of an effectivewave length. It will be noted that straps 37 connect panels 15 and 16 tothe ends of the slot 29 and that straps 38 connect the panels 13 and 14at the ends of the slot 36.

The panel 17 has a side 41, and the panel 18 has a side 42 adjacentthereto to form a slot 43. A feeder line 44 extends from the center ofthe side 41 through a feed hole 22 and is electrically connected to thethird feed line 25. Similarly, a feeder line, not shown, extends fromthe center of the side 42 to the fourth feed line 26. The seventh panel19 has a side 46, and the eighth panel 20 has a side 47 adjacent theretoto form a slot 48. A feeder line, not shown, extends from the center ofthe side 46 to the third feed line 25, and a feeder line 49 extends fromthe center of the side 47 to the fourth feed line 26. Straps 50 join thepanels 17 and 18 at the ends of the slot 43, and straps 51 join thepanels 19 and 20 at the ends of the slot 48.

Triangular panels 54, 55, 56, and 57 are used at the top and the bottomof the antenna to complete the cylindrical antenna 11 but are onlyparasitic panels. If the antenna were to be extended upwardly, thetriangular panels 56 and 57 would become diamond-shaped to form the nexthalf dipoles. It will be observed that the panels 17 and 18 form a thirddipole and the panels 19 and 20 form a fourth dipole, which areenergized in phase and which spiral upwardly to the right which is aspiraling direction opposite that of the dipoles formed by panels 13,14, 15, and 16. Also, the slots 43 and 48 between these panels eachextends about one-fourth the way around the periphery of the antenna andspirals upwardly to the left.

The first and second feed lines 23 and 24 feed the lower dipoles 13 to16, and the third and fourth feed lines 25 and 26 feed the upper dipolesformed from the panels 17 to 20. Thus, the feed lines 23 and 24 form oneopen wire line, and the feed lines, 25 and 26 form another open wireline. Preferably, these two pairs of lines are connected in a degreephase relationship in order to radiate circularly polarizedelectromagnetic waves in the event that the antenna 11 is used as atransmitting antenna.

The antenna 11 of Figures 6 to 9 is shown as being energized across thecenter of each slot 29, 36, 43, and 48. The panels may be energized atthe corners as shown in the parent application Serial No. 780,264, butin this event the straps 37, 38, 50, and 51 would need to be removed.The panel 13 and the panel 17 could be energized at their adjacentcorners to become a vertical dipole, and the panels 14 and 16 could beenergized at their adjacent corners to form a horizontal dipole. Similarconnections could be formed between other panels to produce otherdipoles.

The angle of the slots 29, 36, 43, and 48 has been shown as being 60degrees; however, this can be changed in order to control theellipticity or circularity of the electromagnetic waves.

Although this invention has been described in its pre ferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thecombination and arrangement of parts may be resorted to Withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is:

1. An antenna comprising, a conduit having a peripheral surface and agiven resistivity, first and second spaced edges in the peripheralsurface of said conduit defining a dielectric filled spiral slot thereinof a different resistivity circumscribing at least half the periphery ofsaid surface, and transmission line means connected across said edges.

2. An antenna comprising, a dielectric filled conduit having aperipheral surface and of a given resistivity, first and second spacededges in the peripheral surface of said conduit defining a dielectricfilled slot therein of a different resistivity and the lengthwisedimension of which slot extends both transversely half way around and1ongig tudinally in said conduit, and transmission line means connectedacross said edges. l T

3. An antenna comprising, an electrically conducting conduit, first andsecond spaced edges in said conduit defining a dielectric filled slottherein, the lengthwise dimension of which slot extends bothtransversely and longitudinally in said conduit with the transverseextension circumscribing at least one quarter of the periphery of saidconduit, and transmission line means connected across said edges.

4. An antenna comprising, a hollow electrically conducting conduit,first and second substantially parallel edges in said conduit definingdielectric filled spiral slot means therein, said slot means and saidconduit constituting the entire coupling between said antenna and theambient for a substantially uniform radiation or reception patternperpendicular to said conduit, and transmission line means connectedacross said edges.

5. An antenna for use with electromagnetic waves having horizontal andvertical components and having a substantially non-directional patternin a given plane, said antenna comprising, a hollow electricallyconducting conduit, means for mounting said conduit with the axisthereof perpendicular to said given plane, and substantially paralleledges in said hollow conduit defining twisting slot means extendingsubstantially entirely around said conduit.

6. An antenna for use with electromagnetic waves having horizontal andvertical components and having a substantially non-directional patternin the horizontal plane, said antenna comprising, a hollow electricallyconducting conduit, means for mounting said conduit with the axisthereof in a vertical position, and first and second substantiallyparallel edges in said hollow conduit defining a twisting slot thereinhaving first and second portions together substantially circumscribingsaid conduit.

7. An antenna for use with circularly polarized electromagnetic waveshaving a substantially non-directional pattern in the horizontal plane,said antenna comprising, a hollow electric-ally conducting conduit,means for mounting said conduit with the axis thereof in a verticalposition, and first and second substantially parallel edges in saidhollow conduit defining a slot therein which extends longitudinally insaid conduit as well as transversely substantially entirely around saidconduit.

8. An antenna for use with circularly polarized electromagnetic waveshaving a substantially non-directional pattern in the horizontal plane,said antenna comprising, a hollow cylindrical electrically conductingmember, means for mounting said cylindrical member with the axis thereofin a vertical position, and first and second substantially paralleledges in said hollow cylindrical member defining a generally spiral slottherein extending at least half way around said member.

9. An antenna comprising, a dielectric filled conduit having aperipheral surface of a given resistivity, first and second spaced edgesin the peripheral surface of said conduit defining a dielectric filledslot therein of a different resistivity, said slot extending in ageneral direction of forty-five degrees with the axis of said conduit,said conduit having a peripheral dimension such that said slot completessubstantially one revolution around said conduit.

10. An antenna for use with electromagnetic 'waves comprising, adielectric filled conduit having a peripheral surface of a givenresistivity, first and second spaced edges in the peripheral surface ofsaid conduit defining a dielectric filled slot therein of a differentresistivity, said slot extending in a general direction of forty-fivedegrees with the axis of said conduit, said slot having a lengthsubstantially equal to an elfective wave length of said electromagneticwave, said conduit having a peripheral dimension such that said slotcompletes substantially one revolution around said conduit.

11. An antenna for use with circularly polarized electromagnetic waveshaving a substantially non-directional pattern in the horizontal plane,said antenna comprising, a hollow cylindrical electrically conductingmember, means for mounting said cylindrical member with the axis thereofin a vertical position, first and second substantially parallel edges insaid hollow cylindrical member defining a twisting slot therein, thelengthwise dimension of said twisting slot having an acute angle withthe axis of said cylindrical member, said slot having a length at leastthirty percent of an effective wave length of said electromagnetic wave,a transmission line having first and second conductors and being locatedwithin said hollow cylindrical member, and means for connecting saidfirst and second edges to said first and second conductors,respectively, of said transmission line, said cylindrical member havinga diameter such that said slot effectively extends completely aroundsaid cylindrical member.

12. An antenna for use with circularly polarized electromagnetic waveshaving a substantially non-directional pattern in the horizontal plane,said antenna comprising, a hollow cylindrical electrically conductingmember, means for mounting said cylindrical member with the axis thereofin a vertical position, first and second substantially parallel edgesonly in said hollow cylindrical member defining a spiral slot therein,said spiral slot having an angle of forty-five degrees with the axis ofsaid cylindrical memben said slot having a length substantially equal toan effective wave length of said electromagnetic wave, a transmissionline having two conductors and being located within said hollowcylindrical member, and means for connecting the mid-point of each edgeto one of each said two conductors of said transmission line, saidcylindrical member having a diameter such that said slot completes onerevolution around said cylindrical member.

13. An antenna for use with electromagnetic waves, said antennacomprising, a hollow cylindrical electrically conducting member, meansfor mounting said cylindrical member with the axis thereof in a verticalposition, first and second substantially parallel edges in said hollowcylindrical member defining a first spiral slot therein, third andfourth substantially parallel edges in said hollcw cylindrical memberdefining a second spiral slot therein having a reverse rotationaldirection relative to said first spiral slot, the lengthwise dimensionof each said spiral slot having an acute angle with the axis of saidcylindrical member, said slots having a length at least four-tenths ofan elfective wave length of said electromagnetic wave, said secondspiral slot being axially displaced from said first spiral slot andperipherally positioned one hundred eighty degrees therefrom such thatthe end of said second spiral slot is adjacent the midportion of saidfirst spiral slot, a first and a second transmission line each havingtwo conductors and being located Within said hollow cylindrical member,means for connecting each edge of said first slot to one of each of saidtwo conductors of said first transmission line, means for connectingeach edge of said second slot'to one of each said two conductors of saidsecond transmission line, said cylindrical member having a diameter suchthat said slots complete one revolution around said cylindrical member,and means for connecting said slots in an effective phase displacementof substantially ninety degrees.

14. An antenna for use with circularly polarized electromagnetic waveshaving a substantially non-directional pattern in the horizontal plane,said antenna comprising, a hollow cylindrical electrically conductingmember, means for mounting said cylindrical member with the axis thereofin a vertical position, first and second substantially parallel edges insaid hollow cylindrical member defining a first spiral slot therein,third and fourth substantially parallel edges in said hollow cylindricalmember defining a second spiral slot therein having a reverserotationaldirection relative to said first spiral slot,

.each said spiral slot having an angle of forty-five degrees with theaxis of said cylindrical member, said slots having a lengthsubstantially equal to an effective wave length of said electromagneticwave, said second spiral slot being axially displaced from said firstspiral slot and peripherally positioned one hundred eighty degreestherefrom such that the end of said second spiral slot is adjacent themid-portion of said first spiral slot, at first and a secondtransmission line each having two conductors and being located withinsaid hollow cylindrical member, means for connecting the mid-point ofeach edge of said first slot to one of each of said two conductors ofsaid first trans mission line, means for connecting the mid-point ofeach edge of said second slot to one of each said two conductors of saidsecond transmission line, said cylindrical member having a diameter suchthat said slots complete one revolution around said cylindrical member,and means for connecting said slots in an efiective phase displacementof substantially ninety degrees.

15. An antenna for use with. electromagnetic waves comprising, a hollowcylindrical electrically conducting member, first and secondsubstantially parallel edges in said hollow cylindrical member defininga first spiral slot therein, third and fourth substantially paralleledges in said hollow cylindrical member defining a second spiral slottherein having a reverse rotational direction relative to said firstspiral slot, the lengthwise dimension of each said spiral slot definingan acute angle of sixty degrees with the axis of said cylindricalmember, said slots having a length substantially equal to one-half aneffective Wave length of said electromagnetic wave, said second spiralslot being axially displaced from said first spiral slot andperipherally positioned therefrom, a first and a second transmissionline each having two conductors and being located within said hollowcylindrical member, means for connecting the mid-point of each edge ofsaid first slot to one of each of said two conductors of said firsttransmission line, means for connecting the mid-point of each edge ofsaid second slot to one of each said two conductors of said secondtransmission line, said cylindrical member having a diameter such thateach of said slots completes one-quarter revolution around saidcylindrical member, and means for connecting said slots in an efiectivephase displacement of substantially ninety degrees.

16. A transducer for transferring electromagnetic wave energy betweenfree space and an electrical device utilizing said electromagneticwaves, said transducer comprising electrically conducting conduit means,at least first and second substantially parallel edges in said conduitmeans defining slot means therein, said slot means having a narrow widthrelative to the length thereof, said slot means having a lengthwisedimension with a component aligned parallel to the axis of said conduitmeans and another component aligned transversely to the axis of saidconduit means, the transverse component of the slot means extending atleast one-fourth the distance around said conduit means, andtransmission line means con nected across said slot means.

17. A transducer for transferring electromagnetic wave energy betweenfree space and an electrical device utilizing said electromagneticwaves, said transducer comprising electrically conducting conduit means,at least first and second substantially parallel edges in said conduitmeans defining slot means therein, said slot means having a narrow widthrelative to the length thereof, said slot means having a lengthwisedimension with a component aligned parallel to the axis of said conduitmeans and another component aligned transversely to the axis of saidconduit means, the transverse component of the slot means extendingsubstantially completely around said conduit means, at least part ofsaid conduit means defining a single dielectric filled cavity for saidslot means, and transmission line means connected across said slotmeans.

18. An antenna comprising electrically conducting coniii ' 8 duit meanshaving an axis, a plurality of substantially parallel edges in saidconduit means defining a plurality of slots, said slots being other thanaxially parallel on the periphery of said conduit means, each of saidslots having a length at least equal to four-tenths of said given wavelength, said slots extending at least one-fourth the distance around theperiphery of said conduit means, and transmission line means within theconfines of said conduit means connected across the edges of said slots.

19. An antenna comprising electrically conducting conduit means havingan axis, a plurality of substantially parallel edges in said conduitmeans defining a plurality of slots, said slots being equally spaced andother than axially parallel on the periphery of said conduit means, eachof said siots having a length at least equal to a half of said givenwave length, each of said slots extending substantially completelyaround the periphery of said conduit means, and transmission line meanswithin the confines of said conduit means connected across the center ofeach of said slots.

20. An antenna for circularly polarized electromagnetic waves of a givenwave length with a substantially circular horizontal field intensitypattern, said antenna comprising electrically conducting conduit means,means for mounting said conduit means with the axis thereof in avertical position, first and second substantially parallel edges in saidconduit means defining a first slot, third and fourth substantiallyparallel edges in said conduit means defining a second slot, said slotsbeing substantially parallel and equally spaced on the periphery of saidconduit means and other than axially parallel, each of said slots havinga length at least equal to a half of said given wave length, first feedmeans within the confines of said conduit means connected across atleast the center of each of said slots,

fifth and sixth substantially parallel edges in said conduit meansdefining a third slot, seventh and eighth substantially parallel edgesin said conduit means defining a fourth slot, said third and fourthSlOiS being substantially parallel and equally spaced on the peripheryof said conduit means and other than axiaily parallel, said first andsecond slots twisting in one direction and said third and fourth slotstwisting in the opposite direction, each of. said slots extendingsubstantially completely around the periphery of said conduit means,second feed means within the confines of said conduit means connectedacross at least the center of each of said third and fourth slots, andphasing means for connecting said first and second feed meanssubstantially ninety degrees out or" phase.

21. An antenna comprising an electrically conductive conduit defined byfirst and second sections, the adjacent ends of said sectionsterminating in substantially parallel edges at an acute angle to theaxis of said conduit to define an angular slot, one of said edges beingelectrically connected to one conductor of a feed line and the other Hedge being electrically connected to the other conductor of said feedline.

22. An antenna according to claim 2], in which a rigid pipe passescentrally through one antenna section and having a flange fastened tothe inner periphery of said one section for support thereof, oneconductor of said feed linepassing out through said pipe, and meansconnecting the end of said one conductor to the inner periphery of theother antenna section,

23. An antenna for elliptically polarized field patterns, comprisingcylindrical tubular means having edges defining two twisted slotstogether providing generally elliptical slot means extendingsubstantially entirely around the antenna periphery, and coaxial feedline means having the outer conductor connected to the tubular means onone side of said slot means and the center conductor connected to thetubular means on the opposite side of said slot means.

24. An antenna for use with electromagnetic waves comprising, a hollowcylindrical electrically conducting member, first and secondsubstantially parallel edges in said hollow cylindrical member defininga first twisting slot therein, third and fourth substantially paralleledges in said hollow cylindrical member defining a second twisting slottherein having a reverse rotational direction relative to said firsttwisting slot, the lengthwise dimension of each said slot defining anacute angle with the axis of said cylindrical member, said first andsecond slots together extending substantially completely around saidmember, a first and a second transmission line each having twoconductors and being located within said hollow cylindrical member,means for connecting each edge of said first slot to one of each of saidtwo conductors of said first transmission line, means for connectingeach edge of said second slot to one of each said two "conductors ofsaid second transmission line, andmeans for connecting said slots in anefiective phase displacement of substantially ninety degrees.

25. An antenna for ellipticaly polarized electromagnetic waves, saidantenna comprising electrically conducting conduit means, means formounting said conduit means with the axis thereof in a verticalposition, first and second substantially parallel edges in said conduitmeans defining a first slot, third and fourth substantially paralleledges in said conduit means defining a second slot, said first andsecond slots twisting in opposite directions and together forming slotmeans extending substantially completely around the periphery of saidconduit means, and transmission line means within the confines of saidconduit means connected across said slot means.

26. An antenna comprising a hollow cylinder having a surface themajority of which is conducting except for a narrow strip, said stripextending at an acute angle to the cylinder axis to extend at leastone-half the distance around said cylinder, and transmission line meanselectrically connected to said conducting surface adjacent said strip.

27. An antenna comprising a three-dimensional body having a longitudinalaxis, a conducting external surface on said body having edges definingnarrow strip means, said strip means extending at an acute angle to saidaxis to extend at least one-fourth the distance around said body in adirection transverse to said axis to thus have longitudinal andtransverse components, and transmission line means electricallyconnected to the edges of said strip for transfer therebetween ofelliptically polarized electromagnetic wave energy having longitudinaland transverse components.

28. An antenna structure for transmitting and receiving ellipticallypolarized waves which may be defined from the transmission point ofview, as comprising a conduit having an axis and having a slot shapedaperture extending at an angle to said axis for radiating a first wavepolarized at a first angle to said axis, means including a second slotshaped aperture extending at a second angle to said axis for radiating asecond wave polarized at a second angle to said axis, transmission linemeans connected to said apertures to provide a time quadraturedisplacement of said first and second polarized waves thereby toeffectively radiate an elliptically polarized wave.

29. An antenna structure for transmitting and receiving ellipticallypolarized waves which may be defined from the transmission point ofview, as comprising a conduit having an axis and having a slot shapedaperture for radiating a first wave polarized at a first angle to saidaxis, means for radiating a second wave polarized at a second angle tosaid axis, transmission line means connected to said aperture and tosaid means to provide a time quadrature displacement of said first andsecond polarized waves thereby to eflectively radiate an ellipticallypolarized wave.

References Cited in the file of this patent UNITED STATES PATENTS2,129,712. Southworth Sept. 13, 1938 2,479,227 Gilbert Aug. 16, 19492,562,332 Riblet July 31, 1951 2,600,179 Alford June 10, 1952 2,643,337Nail June 23, 1953 2,647,212 Feldman July 28, 1953

